Comment # 29 on bug 1200461 from Thomas Blume

(In reply to Mike DeMicco from comment #28)
> FYI, there was a change to dracut-functions.sh that invoked "udevadm info
> -a." Older versions of this shell script do not do this (e.g., the 15.3
> version of Leap, vs. latter versions). This is the change that caused the
> problem on my system.

Ok, still, 'updevadm info -a' should not hang your computer.
Unfortunately, the udev debug logs didn't make it into the dmesg output.
But I've found a resource conflict with your i/o controller:

-->
[   13.209692] ACPI Warning: SystemIO range
0x0000000000000428-0x000000000000042F conflicts with OpRegion
0x000000000000042C-0x000000000000042D (\GP2C) (20211217/utaddress-204)
[   13.209701] ACPI: OSL: Resource conflict; ACPI support missing from driver?
[   13.211431] lpc_ich: Resource conflict(s) found affecting gpio_ich
--<

Such conflicting resources could probably cause a system hang when they are
accessed by udevadm via sysfs.